1. Field of the Invention
The present invention relates to a catalyst for reforming that is employed when producing synthetic gas by reacting hydrocarbon such as methane with a reforming agent such as water, carbon dioxide, oxygen, air or the like. The present invention further relates to a process for producing synthetic gas employing this catalyst for reforming. The synthetic gas is a mixed gas containing carbon monoxide (CO) and hydrogen (H2).
The present specification is based on a patent application filed in Japan (Japanese Patent Application No. Hei. 11-98220), the contents of which are incorporated herein by reference.
2. Description of the Related Art
It has been the conventional practice to carry out reforming by reacting hydrocarbon such as methane, natural gas, petroleum gas, naphtha, heavy oil, crude oil or the like, and a reforming agent such as water, air, oxygen, or carbon dioxide at high temperature in the presence of a catalyst, to generate a highly reactive synthetic gas. Methanol or liquid fuels are then produced by employing this generated synthetic gas as a source material.
Ni/Al2O3 catalyst, Ni/MgO/Al2O3 catalyst or the like may be applied as examples of reforming catalysts used in reforming reactions.
However, when stoichiometric equivalents of methane and steam are reacted during reforming employing these types of catalysts for reforming, for example, a problem arises in that considerable deposition of carbonaceous matters (carbon) occurs. Accordingly, in order to prevent deposition of this carbonaceous matters, a large excess of steam is supplied to the reactor, to accelerate the reforming reaction.
As a result, reforming reactions as conventionally performed requires a large amount of steam, leading to such undesirable consequences as increased energy costs and larger facilities.
It is the objective of the present invention to prevent the deposition of carbonaceous matters when producing synthetic gas by adding a stoichiometric equivalent, or an amount near the stoichiometric equivalent, of a reforming agent to hydrocarbon.
This subject can be resolved by employing a compound that is a mixed oxide having the composition expressed by the following formula in which M and Co are more highly dispersed as the catalyst for reforming.
aM.bCo.cMg.dCa.eO
(Where, a, b, c, d, and e are molar fractions, a+b+c+d=1, 0.0001xe2x89xa6axe2x89xa60.10, 0.0001xe2x89xa6bxe2x89xa60.20, 0.70xe2x89xa6(c+d)xe2x89xa60.9998, 0 less than cxe2x89xa60.9998, 0xe2x89xa6d less than 0.9998, and e=the number of oxygen necessary to maintain an electric charge balance with metallic elements. M is at least one type of element selected from among the group VIA elements, group VIIA elements, group VIII transition elements excluding Co, group IB elements, group IIB elements, group IVB elements and lanthanoid elements in the periodic table.)
The present invention employs as the catalyst for reforming the mixed oxide in which M and Co are more highly dispersed. As a result, even when reacting the stoichiometric equivalent, or an amount near the stoichiometric equivalent, of the hydrocarbon and the reforming agent, it is possible to suppress deposition of carbonaceous matters (carbon). Accordingly, the synthetic gas can be obtained with high efficiency, and production costs can be reduced. Moreover, the catalyst is not contaminated by the carbonaceous matters, so that deterioration in catalytic activity over time is prevented, and the life of the catalyst can be extended.